﻿using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using System.Web;

namespace Gaga.Core
{
	public partial class CommonHelper
	{
		/// <summary>
		/// Ensures the subscriber email or throw.
		/// </summary>
		/// <param name="email">The email.</param>
		/// <returns></returns>
		public static string EnsureSubscriberEmailOrThrow(string email)
		{
			string output = EnsureNotNull(email);
			output = output.Trim();
			output = EnsureMaximumLength(output, 255);

			if (!IsValidEmail(output))
			{
				throw new GagaException("Email is not valid.");
			}

			return output;
		}

		/// <summary>
		/// Verifies that a string is in valid e-mail format
		/// </summary>
		/// <param name="email">Email to verify</param>
		/// <returns>true if the string is a valid e-mail address and false if it's not</returns>
		public static bool IsValidEmail(string email)
		{
			if (String.IsNullOrEmpty(email))
				return false;

			email = email.Trim();
			var result = Regex.IsMatch(email, "^(?:[\\w\\!\\#\\$\\%\\&\\'\\*\\+\\-\\/\\=\\?\\^\\`\\{\\|\\}\\~]+\\.)*[\\w\\!\\#\\$\\%\\&\\'\\*\\+\\-\\/\\=\\?\\^\\`\\{\\|\\}\\~]+@(?:(?:(?:[a-zA-Z0-9](?:[a-zA-Z0-9\\-](?!\\.)){0,61}[a-zA-Z0-9]?\\.)+[a-zA-Z0-9](?:[a-zA-Z0-9\\-](?!$)){0,61}[a-zA-Z0-9]?)|(?:\\[(?:(?:[01]?\\d{1,2}|2[0-4]\\d|25[0-5])\\.){3}(?:[01]?\\d{1,2}|2[0-4]\\d|25[0-5])\\]))$", RegexOptions.IgnoreCase);
			return result;
		}

		/// <summary>
		/// Generate random digit code
		/// </summary>
		/// <param name="length">Length</param>
		/// <returns>Result string</returns>
		public static string GenerateRandomDigitCode(int length)
		{
			var random = new Random();
			string str = string.Empty;
			for (int i = 0; i < length; i++)
				str = String.Concat(str, random.Next(10).ToString());
			return str;
		}

		/// <summary>
		/// Returns an random interger number within a specified rage
		/// </summary>
		/// <param name="min">Minimum number</param>
		/// <param name="max">Maximum number</param>
		/// <returns>Result</returns>
		public static int GenerateRandomInteger(int min = 0, int max = int.MaxValue)
		{
			var randomNumberBuffer = new byte[10];
			new RNGCryptoServiceProvider().GetBytes(randomNumberBuffer);
			return new Random(BitConverter.ToInt32(randomNumberBuffer, 0)).Next(min, max);
		}

		/// <summary>
		/// Ensure that a string doesn't exceed maximum allowed length
		/// </summary>
		/// <param name="str">Input string</param>
		/// <param name="maxLength">Maximum length</param>
		/// <param name="postfix">A string to add to the end if the original string was shorten</param>
		/// <returns>Input string if its lengh is OK; otherwise, truncated input string</returns>
		public static string EnsureMaximumLength(string str, int maxLength, string postfix = null)
		{
			if (String.IsNullOrEmpty(str))
				return str;

			if (str.Length > maxLength)
			{
				var result = str.Substring(0, maxLength);
				if (!String.IsNullOrEmpty(postfix))
				{
					result += postfix;
				}
				return result;
			}

			return str;
		}

		/// <summary>
		/// Ensures that a string only contains numeric values
		/// </summary>
		/// <param name="str">Input string</param>
		/// <returns>Input string with only numeric values, empty string if input is null/empty</returns>
		public static string EnsureNumericOnly(string str)
		{
			if (String.IsNullOrEmpty(str))
				return string.Empty;

			var result = new StringBuilder();
			foreach (char c in str)
			{
				if (Char.IsDigit(c))
					result.Append(c);
			}
			return result.ToString();
		}

		/// <summary>
		/// Ensure that a string is not null
		/// </summary>
		/// <param name="str">Input string</param>
		/// <returns>Result</returns>
		public static string EnsureNotNull(string str)
		{
			if (str == null)
				return string.Empty;

			return str;
		}

		/// <summary>
		/// Indicates whether the specified strings are null or empty strings
		/// </summary>
		/// <param name="stringsToValidate">Array of strings to validate</param>
		/// <returns>Boolean</returns>
		public static bool AreNullOrEmpty(params string[] stringsToValidate)
		{
			bool result = false;
			Array.ForEach(stringsToValidate, str => {
				if (string.IsNullOrEmpty(str)) result = true;
			});
			return result;
		}

		/// <summary>
		/// Compare two arrasy
		/// </summary>
		/// <typeparam name="T">Type</typeparam>
		/// <param name="a1">Array 1</param>
		/// <param name="a2">Array 2</param>
		/// <returns>Result</returns>
		public static bool ArraysEqual<T>(T[] a1, T[] a2)
		{
			//also see Enumerable.SequenceEqual(a1, a2);
			if (ReferenceEquals(a1, a2))
				return true;

			if (a1 == null || a2 == null)
				return false;

			if (a1.Length != a2.Length)
				return false;

			var comparer = EqualityComparer<T>.Default;
			for (int i = 0; i < a1.Length; i++)
			{
				if (!comparer.Equals(a1[i], a2[i])) return false;
			}
			return true;
		}

		private static AspNetHostingPermissionLevel? _trustLevel;
		/// <summary>
		/// Finds the trust level of the running application (http://blogs.msdn.com/dmitryr/archive/2007/01/23/finding-out-the-current-trust-level-in-asp-net.aspx)
		/// </summary>
		/// <returns>The current trust level.</returns>
		public static AspNetHostingPermissionLevel GetTrustLevel()
		{
			if (!_trustLevel.HasValue)
			{
				//set minimum
				_trustLevel = AspNetHostingPermissionLevel.None;

				//determine maximum
				foreach (AspNetHostingPermissionLevel trustLevel in new[] {
								AspNetHostingPermissionLevel.Unrestricted,
								AspNetHostingPermissionLevel.High,
								AspNetHostingPermissionLevel.Medium,
								AspNetHostingPermissionLevel.Low,
								AspNetHostingPermissionLevel.Minimal
							})
				{
					try
					{
						new AspNetHostingPermission(trustLevel).Demand();
						_trustLevel = trustLevel;
						break; //we've set the highest permission we can
					}
					catch (System.Security.SecurityException)
					{
						continue;
					}
				}
			}
			return _trustLevel.Value;
		}

		/// <summary>
		/// Sets a property on an object to a valuae.
		/// </summary>
		/// <param name="instance">The object whose property to set.</param>
		/// <param name="propertyName">The name of the property to set.</param>
		/// <param name="value">The value to set the property to.</param>
		public static void SetProperty(object instance, string propertyName, object value)
		{
			if (instance == null) throw new ArgumentNullException("instance");
			if (propertyName == null) throw new ArgumentNullException("propertyName");

			Type instanceType = instance.GetType();
			PropertyInfo pi = instanceType.GetProperty(propertyName);
			if (pi == null)
				throw new GagaException("No property '{0}' found on the instance of type '{1}'.", propertyName, instanceType);
			if (!pi.CanWrite)
				throw new GagaException("The property '{0}' on the instance of type '{1}' does not have a setter.", propertyName, instanceType);
			if (value != null && !value.GetType().IsAssignableFrom(pi.PropertyType))
				value = To(value, pi.PropertyType);
			pi.SetValue(instance, value, new object[0]);
		}


		public static TypeConverter GetNopCustomTypeConverter(Type type)
		{
			//we can't use the following code in order to register our custom type descriptors
			//TypeDescriptor.AddAttributes(typeof(List<int>), new TypeConverterAttribute(typeof(GenericListTypeConverter<int>)));
			//so we do it manually here

			if (type == typeof(List<int>))
				return new GenericListTypeConverter<int>();
			if (type == typeof(List<decimal>))
				return new GenericListTypeConverter<decimal>();
			if (type == typeof(List<string>))
				return new GenericListTypeConverter<string>();

			return TypeDescriptor.GetConverter(type);
		}

		/// <summary>
		/// Converts a value to a destination type.
		/// </summary>
		/// <param name="value">The value to convert.</param>
		/// <param name="destinationType">The type to convert the value to.</param>
		/// <returns>The converted value.</returns>
		public static object To(object value, Type destinationType)
		{
			return To(value, destinationType, CultureInfo.InvariantCulture);
		}

		/// <summary>
		/// Converts a value to a destination type.
		/// </summary>
		/// <param name="value">The value to convert.</param>
		/// <param name="destinationType">The type to convert the value to.</param>
		/// <param name="culture">Culture</param>
		/// <returns>The converted value.</returns>
		public static object To(object value, Type destinationType, CultureInfo culture)
		{
			if (value != null)
			{
				var sourceType = value.GetType();

				TypeConverter destinationConverter = GetNopCustomTypeConverter(destinationType);
				TypeConverter sourceConverter = GetNopCustomTypeConverter(sourceType);
				if (destinationConverter != null && destinationConverter.CanConvertFrom(value.GetType()))
					return destinationConverter.ConvertFrom(null, culture, value);
				if (sourceConverter != null && sourceConverter.CanConvertTo(destinationType))
					return sourceConverter.ConvertTo(null, culture, value, destinationType);
				if (destinationType.IsEnum && value is int)
					return Enum.ToObject(destinationType, (int)value);
				if (!destinationType.IsInstanceOfType(value))
					return Convert.ChangeType(value, destinationType, culture);
			}
			return value;
		}

		/// <summary>
		/// Converts a value to a destination type.
		/// </summary>
		/// <param name="value">The value to convert.</param>
		/// <typeparam name="T">The type to convert the value to.</typeparam>
		/// <returns>The converted value.</returns>
		public static T To<T>(object value)
		{
			//return (T)Convert.ChangeType(value, typeof(T), CultureInfo.InvariantCulture);
			return (T)To(value, typeof(T));
		}

		/// <summary>
		/// Convert enum for front-end
		/// </summary>
		/// <param name="str">Input string</param>
		/// <returns>Converted string</returns>
		public static string ConvertEnum(string str)
		{
			string result = string.Empty;
			char[] letters = str.ToCharArray();
			foreach (char c in letters)
				if (c.ToString() != c.ToString().ToLower())
					result += " " + c.ToString();
				else
					result += c.ToString();
			return result;
		}

		/// <summary>
		/// Set Telerik (Kendo UI) culture
		/// </summary>
		public static void SetTelerikCulture()
		{
			//little hack here
			//always set culture to 'en-US' (Kendo UI has a bug related to editing decimal values in other cultures). Like currently it's done for admin area in Global.asax.cs

			var culture = new CultureInfo("zh-CN");
			Thread.CurrentThread.CurrentCulture = culture;
			Thread.CurrentThread.CurrentUICulture = culture;
		}

		/// <summary>
		/// Get difference in years
		/// </summary>
		/// <param name="startDate"></param>
		/// <param name="endDate"></param>
		/// <returns></returns>
		public static int GetDifferenceInYears(DateTime startDate, DateTime endDate)
		{
			//source: http://stackoverflow.com/questions/9/how-do-i-calculate-someones-age-in-c
			//this assumes you are looking for the western idea of age and not using East Asian reckoning.
			int age = endDate.Year - startDate.Year;
			if (startDate > endDate.AddYears(-age))
				age--;
			return age;
		}
	}
}
